Physical
activity (PA) in children has a decisive role in motor development and prevention
of childhood obesity. The available evidence suggests that there is high prevalence
of low levels of PA in children, but little is known about the level of PA in
preschool children. The objective of this study was to identify the prevalence
and the factors associated with low levels of PA in preschool children. This was
a cross-sectional study performed in private schools in the municipality of Olinda
(state of Pernambuco), with data collection through parent's face-to-face interviews.
The study included 265 children (54.3% girls) with mean age of 4.9 years (SD=0.8).
Children who did not perform at least 60 minutes/day of outdoors physical activities
were considered exposed to low levels of PA. Data analysis was performed by logistic
regression considering low level of PA as the outcome. The results showed that
65.3% (95%CI: 9.4-70.8) of children were classified as exposed to 'low level of
PA'. Analysis showed that higher parental education (OR=2.41; 95%CI: 1.13-5.10),
lack of space for playing at home (OR=2.36; 95%CI: 1.17- 4.78), and attending
school in the afternoon (OR=2.92, 95%CI 1.55-5.49) or full-time (OR=57.1, 95%CI
6.57-496.2) were associated with low levels of PA. Preschoolers from families
with higher number of children had lower likelihood of low level of PA (OR=0.49;
95%CI 0.26-0.93). It can be concluded that the proportion of children exposed
to low levels of PA is high compared to the results of similar studies and that
parental and environmental factors are associated with physical activity level
in preschool-aged children.

Key
words: Epidemiology; Motor activity; Preschool.

INTRODUCTION

Studies
have shown that physical inactivity in childhood is linked to various health-risk
conditions in adulthood1,2. Low levels of physical activity are among
the possible determinants of childhood obesity3,4. Furthermore, a recent
study by Tanha et al.5 also showed that a low level of moderate to
vigorous physical activity is significantly related to higher rates of cardiovascular
risk in children from 8 to 11 years old.

Besides
its connection with acute and chronic health outcomes, lack of physical activity
in childhood may be associated with physical inactivity in adolescence and adult
life. However, the available findings are controversial and although there is
evidence that physical activity in preschoolers is associated with physical activity
in later stages of life6,7, in the study conducted by Mattocks et al.8
they found the opposite.

The
time preschoolers spend in sedentary activities (watching TV, playing video game)
is associated to negative health outcomes, such as overweight and obesity in older
ages9,10. Besides controlling weight, the practice of physical activity
at this stage of life seems to have an effect on bone mineral density, motor performance
and on psychosocial factors, such as self-esteem and self-image, among others11.

Despite
the methodological difficulties involved in physical activity assesment12,
results of studies with preschool children showed a low level of physical activity
in this population13,14. But there is a lack of data regarding the
prevalence of low physical activity in preschoolers and even less data on convergent
evidence concerning the factors that are associated to this condition in this
subgroup. For instance, the study by GrØntved et al.15 revealed
that the socio-economic status is not associated to the level of physical activity,
but Batty and Leon16 conducted a systematic review which demonstrated
the opposite.

Despite
all the efforts of the scientific community, there are few studies describing
the level of physical activity and associated factors in preschoolers, particularly,
in developing countries like Brazil. The study of Romaldine, Issler et al.17
was the only publication so far found to make a standard measure of physical activity
in preschool children in Brazil (municipality of São Paulo). However, the
study covered a sample of 109 subjects, quite heterogeneous regarding age (2 to
20 years) and whose measure of physical activity was based only on the weekly
frequency of structured physical activity.

Given
the above, the aim of the present study was to identify the prevalence and the
demographic, socioeconomic and environmental factors related to the low level
of physical activity in preschool children.

METHODS

School-based
cross-sectional study conducted in the municipality of Olinda, state of Pernambuco.
Data collection was performed between October and December 2004. The protocol
of the present investigation was approved by the Research Ethics Committee of
the Universidade Federal de Santa Catarina (project n. 062/2004).

The
population of the study was limited to children attending private schools in the
municipality of Olinda, with age range from 4 to 6 years, estimated, at the time,
in around 9,500 children distributed in 128 preschools. For the selection of subjects,
the technique of two-stage random sampling was used. Initially, 19 schools were
selected, representing, approximately 15% of total education units. The definition
of this quantitative of schools was due to logistical limitations to conduct the
fieldwork within the period of 3 months. Schools that have not authorized the
study (n=6) were replaced by the immediately preceding on the numbered list used
in the selection process. The reasons for refusal were the existence of school
rules which were contrary to the conduction of research or because the conduction
of work of this nature could interfere in the dynamics of school activities.

In
the following stage, after contacting the schools and obtaining permission to
conduct the study, 10 children were randomly selected per shift (morning and afternoon)
in each of the selected schools. In full-time schools, 20 children were randomly
selected. For instance, in a school with four classes, two in the morning shift
and two in the afternoon shift, five children were randomly selected from each
class, hypothetically totaling 20 subjects in this school. The selection of children
was made considering the order of names presented in teachers' roll calls. Following
these sample procedures and the number of preschool classes existing in the selected
schools, it would be possible to achieve a sample of up to 310 subjects.

For
data collection, we used a questionnaire answered by parents in the form of face-to-face
interviews. The instrument containing 38 closed questions was constructed by adapting
the questionnaire proposed by the team responsible for the project "Study of Childhood
Obesity in Florianópolis"18. The adjustments made included the
review of question wording, which went from a self-report format to face-to-face
interview, and the inclusion of a section related to the physical activity measurement
of the instrument proposed by Burdette et al.19. The interviews were
answered only by the father or the mother of the selected children.

Validity
of the instrument used specifically for obtaining measurements of physical activity
was tested against direct measurement of physical activity obtained through motion
sensors19. Additionally, parents of 20 children (10 boys and e 10 girls)
of a private school on the outskirts of the metropolitan area of Recife were interviewed
individually in two separate occasions, one week apart. It was observed that the
questions were easily answered by interviewees. The time to answer the entire
interview ranged from 8 to 15 minutes, and the mean time was around 12 minutes.
Regarding the consistency of the test-retest measures, reproducibility coefficients
(Spearman correlation coefficient) of 0.51 and 0.48 were found for the measurement
of at home and outdoor playtime, respectively. Identification data, as well as
demographic and behavioral variables obtained through the questionnaire presented
coefficients of test-retest reliability always higher than 0.85.

Four
questions of the instrument concerned the time spent in games and sports. Each
question allowed tracing the place (garden/backyard or outside the household),
period of the week (weekday, weekend day) and period of the day (from the time
the child wakes up until noon; from noon to 6; from 6 until bedtime) in which
the activities were performed. The amount of time spent in physical activities
was classified by the parents, who had five answer options (0, 1-15, 16-30, 31-60,
>60 minutes). To analyze the data, the classification made by parents, considering
the five categories of time, was converted to an ordinal scale from 0 to 4 points
(0=0 minutes, 1=1-15 minutes, 2=16-30 minutes, 3=31-60 minutes, 4=more than 60
minutes). From the answers, we proceeded to identify the children who performed
less than 60 minutes/day in outdoor playtime, and these cases were classified
as 'low level of physical activity' (outcome).

The
following variables were considered as potential associated factors: sex; age;
parents marital status (single, married, other); maternal and paternal education;
number of children (1, 2 or more); firstborn son (yes, no); breastfed (yes, no);
practice of physical activity by parents; type of housing (apartment, house);
space for outdoor play at home (yes, no); shift (morning, afternoon, full-time);
active transportation from home to school (yes, no); participation in sports outside
the school (yes, no). The data on maternal and paternal education level was collected
through the following questions: "until what grade did you study?" and "until
what grade did your partner or spouse study?" The answers were then classified
into three categories: incomplete high school or lower, complete high school or
higher. Similarly, the data related to parents physical activity levels were obtained
through the following questions: "do you practice physical activity?" and does
your partner or spouse practice physical activity?" The responses were recorded
as dichotomous (yes, no) responses by the interviewers.

The
data collected in the investigation were entered in a database by using the EpiData
2.0 software and later processed and analyzed by using the SPSS (version 11).
The analysis covered the use of descriptive procedures, chi-square test and binary
logistic regression. In logistic regression the backward stepwise conditional
method was used, adopting p>0.20 as exclusion criteria for the model variables.

A
posteriori sample calculations were performed to estimate the statistical power
of the analysis. To identify the prevalence of low physical activity levels, without
resorting to the correction for the sample design effect, it was verified that
this sample size would allow to identify estimated prevalence of 30%, with 80%
power, 95% confidence interval and sampling error of five percentage points. For
the association analysis, it was found that it would be possible to detect as
significant OR values that were equal or greater than 2, considering 80% power,
95% confidence interval and 65% outcome prevalence among the non-exposed.

RESULTS

The
final sample had 265 subjects (response rate of 85.5% compared to the sample originally
projected). Parents of 35 children could not be reached in school because they
used a private service of transportation, thus the interviews were not possible.
Other two refused to participate and decided to discontinue participation during
the interview. Eight questionnaires were excluded after the phase of entering
data, because the age of subjects was less than 4 years old.

The
characteristics of the children included in the study are presented in Table
1. The mean age was 4.9±0.8 years, significantly higher (p=0.04) among
girls (5.0±0.9 years) when compared to boys (4.8±0.8 years). There were
no statistically significant differences between boys and girls in relation to
any of the independent variables under analysis in this study, except in relation
to age, as previously mentioned.

Time
spent commuting to school was significantly higher (p=0.01) for children who traveled
by motor vehicles (~14 minutes), compared to children who performed the journey
on foot (~11 minutes). It was also found that 89% (n=231) of children did not
practice any sports outside the school. Most of the remaining children (11%; n=29),
practiced sports outside the school up to twice a week. Swimming was the most
common form of activity among children of this age group. At school, in addition
to Physical Education and recreation, it was verified that some children participate
in other types of structured sports activities: martial arts, dancing and basketball.
Combining the data on participation in structured sports activities in and outside
school, it was found that 32 children (12.3%) participated in at least one activity.

It
was verified that 65.3% (95%CI: 59.4-70.8) of children were classified as exposed
to 'low level of physical activity', and it was observed that this proportion
did not differ significantly (c2=0.80; p=0.37) among boys (67.8%; 95%CI: 59.1-75.6)
and girls (62.5%; 95%CI: 54.4-70.1). In bivariate analysis, we found that only
two factors were associated to the level of physical activity: the shift the child
attends school (p<0.01) and the availability of physical spaces for participation
in outdoor play at home (p<0.01). These results are presented in Figure
1.

Analysis
of bivariate binary logistic regression between each of the independent variables
and the outcome under analysis (low level of physical activity) are presented
in Table 2. In multivariate
analysis (binary logistic regression), it was found that four factors are associated
with low level of physical education in this group: paternal education, number
of offspring, availability of physical spaces for outdoor play at home and the
shift in which the child attends school. The final regression model is capable
of explaining, approximately, 23% of the variability in physical activity behavior
in this group of subjects. The results are presented in Table 3.

DISCUSSION

The
development of the present study provided some important findings: the prevalence
of preschool children exposed to low level of physical activity is high, affecting,
approximately, two out of three children; two parental factors (number of offspring
and parental education level) are significantly associated with the level of physical
activity of the children; lack of outdoor play areas at home is a risk factor
for low level of physical activity; and the children studying in the afternoon
or full-time are exposed to greater risk compared to those studying in the morning.

On
the other hand, while providing interesting evidence, caution is recommended in
generalizing the results of this study due to some possible limitations. First,
the operational difficulty in conducting face-to-face interviews outside the school
environment was the main reason for the exclusion of 35 participants, implying
a sample loss of 13%, which, though small, does not exclude the possibility of
selection bias. However, participants were selected through random sampling and
this procedure may have reduced the occurrence of this type of bias.

The
use of measures reported by parents instead of adopting an objective measure or
a combination of measures (e.g. questionnaire and direct monitoring) might also
have been a source of bias. We tried to avoid this problem by using a previously
tested instrument that was applied by personnel who have been trained for this
activity.

The
quantitative definition of schools to 15% of the total existing in the municipality
where the study was conducted resulted from logistics and timing conditions (three
months) for completion of the fieldwork (data collection). This methodological
approach may have limited the sample size and the precision of prevalence estimates.
In addition, some factors may not have been identified as being associated with
low activity level due lack of statistical power.

The
lack of population-based or school-based studies focusing on the practice of physical
activities in Brazilian preschool children does not allow the comparison of the
results obtained in this study with others. Regarding international studies, Kagamimori
et al.20 took the time children spend on outdoor play and sports as
a measure of the level of physical activity, adopting time inferior to 60 minutes
as the cutoff point to classify subjects with low level of physical activity.
The results of an investigation with a cohort of almost 10 thousand 3-year-old
Japanese children, showed a prevalence of 58.1% subjects classified with low level
of physical activity. Despite a difference of 7.1 percentage points in relation
to the verified in the present study, the results converge to alert to the low
level of physical activity to which Brazilian preschool children may be exposed
nowadays.

Although
there is evidence that both paternal and maternal factors may be correlated to
the level of physical activity in preschool-aged children21, the education
level of the mothers and not that of the fathers seem to be associated with behavior
regarding the practice of physical activities, as reported by Van Rossem et al.22.
However, in the present study, the opposite was observed. The explanation for
this discrepancy in results may lie in the fact that cultural characteristics
that change from one social group to another may act as mediators of the association
between parental factors and children's behavior. Thus, in certain social groups,
maternal education may have a more important role and in others, as observed in
the present study, paternal schooling may explain more about the variability in
children's behavior regarding the practice of physical activities. Another possible
explanation for the differences in studies results lies in the greater heterogeneity
of education levels observed in the Brazilian population as a whole compared to
that observed in countries with high economic development.

The
results of the present study indicate that preschool-aged children from families
with two or more children have, approximately, 50% lower likelihood of being exposed
to low levels of physical activity compared to those who are only children. The
association between the number of children in the family and level of physical
activity is an almost unexplored topic23, particularly, in preschool-aged
children24. However, it is plausible to suggest that a greater number
of children and, therefore, siblings, increase the chance that the child participates
in games and activities more physically active.

One
line of investigation that has received much attention in recent years is the
analysis of how the environmental characteristics (physical and social) may influence
the level of physical education25. In the present study, it was verified
that the children who lived in a place where there was no physical space for outdoor
play had a 136% higher chance of having a low level of physical activity, converging
to the findings reported by Timperio et al.26. Despite pointing in
the same direction, only around 30% of studies conducted with subjects aged 3-12
years found evidence of association between the recreational environment and the
level of physical activity of the subjects25.

Another
important finding of the present study was the identification of the fact that
the children who study in the afternoon or full-time had higher likelihood of
presenting low level of physical activity. Possibly, children who study in the
morning may perform outdoor physical activities in the afternoon because the conditions
of temperature and solar exposition allow these practices after 4 p.m. However,
those who study in the afternoon, would need to have their parents or caregivers
availability to perform this activities in the first hours of the day, once after
8 a.m. the exposure to sunlight and the temperature are not recommended or tolerable
for children in this age group, particularly, in the region where this study was
conducted (northeastern Brazil).

Considering
the results of this study, it was concluded that the proportion of children exposed
to low levels of PA (approximately two out of three) is high in comparison to
the similar studies. It was also found that both parental (paternal education
and number of children) and environmental factors (availability of physical space
for playing at home) are associated with the level of physical activity in preschool-aged
children.

Actions
should be developed to inform teachers, parents, directors of education units
and public sectors about the importance of physical activity for preschool-aged
children. Within the school, actions should be conducted in order to encourage
the creation of more and better opportunities to perform physical activities (games
and sports), particularly, for those studying full-time. Finally, during the development
of this study, new knowledge gaps were found, thus further investigation will
be necessary to expand the body of knowledge about the "physical activity-health"
interrelation in the context of early childhood education. The association between
environmental factors and physical activity levels observed in the present study
suggests that the promotion of physical activity in this age group may occur through
physical environmental modification, but this hypothesis will need to be tested
in intervention studies. There is also a need to develop prospective studies in
order to identify determinants of physical activity behavior within this population
subset.